Injection molding controller interface with user-adjustable variables

ABSTRACT

An injection molding machine uses a native controller and a retrofit controller to effectively control its operation. The controllers may determine and/or receive information regarding the machine&#39;s maximum load capacity, and may also determine a current operational load value of the machine. The retrofit controller may cause the machine to operate at any number of combinations of settings of operational parameters which result in the machine operating at or below the maximum load value by adjusting any number of machine parameters associated with the injection molding machine based on feedback sensors measuring real-time operating conditions of the machine.

FIELD OF THE INVENTION

The present application generally relates to injection molding and, morespecifically, to approaches for retrofitting an injection moldingmachine with a secondary controller to control operation thereof, whichcan reduce the energy required to form a molded article.

BACKGROUND OF THE INVENTION

Injection molding is a technology commonly used for high-volumemanufacturing of parts constructed of thermoplastic materials. Duringrepetitive injection molding processes, a thermoplastic resin, typicallyin the form of small pellets or beads, is introduced into an injectionmolding machine which melts the pellets under heat and pressure. Themolten material is then forcefully injected into a mold cavity having aparticular desired cavity shape. The injected plastic is held underpressure in the mold cavity and subsequently is cooled and removed as asolidified part having a shape closely resembling the cavity shape ofthe mold. A single mold may have any number of individual cavities.

Conventional injection molding machines operate withinmanufacturer-provided constraints to ensure safety and operability ofthe machine. These machines are typically constrained by maximum loadvalues which act to limit any number of operating parameters of theinjection molding machine to ensure safe and effective operability andavoid damage to components of the injection molding machine. In theevent that the manufacturer's safety margin level, as contrasted to themachine's actual maximum load value for a given set of operating andenvironmental conditions, is exceeded, the machine may overheat, trip toa failsafe setting, and/or trigger an alarm condition. The maximum loadvalue may be represented graphically, and it may be dependent on anynumber of variables, such as, for example, equipment operating speeds,pressures, the type and viscosity of material(s) being molded, as wellas environmental conditions. Because of the presence of maximum loadvalues, the machine may be permanently configured to operate at or belowparticular variables regardless of whether the machine is operatingabove the maximum allowable load prescribed by the manufacturer.

Generally speaking, injection molding machines allow an operator tomodify and/or manipulate the operating parameters thereof. As a merelyillustrative, non-limiting example, if an environmental factor such as aplant ambient temperature causes the injection molding machine to workharder to generate parts, the machine's operating load value over agiven period of time will increase. This increase in the operationalload value may eventually cause the machine to approach or exceed themaximum load value which may result in temporary or permanent machinefailure. Prior to exceeding or even reaching this maximum load value,the machine may be pre-programmed to generate an alarm which prompts amachine operator to adjust operating variables as required to lower theoperating load on the machine, or may trigger the machine to reduce oreven cease molding operations altogether, i.e. trip to a safety mode.

By relying on the machine operator to adjust operating parameters of themachine, adjustments may not be made as frequently as optimal. Forexample, if the injection molding machine is operating overnight with alimited number of operators on duty, there may be an extended period inwhich parameters are not altered. Further, an operator may not realizewhen the characteristics causing the machine's load value to change havesubsided, and thus may keep the machine running in an operational modewhich fails to fully utilize the injection molding machine's efficiency.Further still, different operators may employ different approaches toadjusting the machine, and some operators may be less inclined to adjustsettings as frequently as others.

Machines may be configured to provide a safety margin below a maximummachine load based on a “worst-case scenario,” that is, when any numberof parameters are present that would dramatically impact operability ofthe machine. The restrictions applied to the machines (e.g., safetyfactors) may restrict the machine from operating within a certainpercentage of the maximum machine load. As a result, in operatingconditions that resemble the worst-case scenario (such as environmentswith high ambient temperatures and/or pressures, materials havingabnormally high viscosities, thus impacting flow speeds and coolingtimes, and the like), the machine is limited to performing at a levelthat is less than its peak performance. Similarly, even in the presenceof operating conditions which are considered favorable or preferred, dueto the fact that the manufacturer's pre-programmed safety factors areset with worst-case scenarios in mind, and are often not easilyoverridden, it is often the case that conventional injection moldingsystems do not approach peak efficiency outputs, even in the most idealof operating conditions.

Frequently, injection molding machines are configured by themanufacturer to fix the range of adjustability of certainoperator-adjustable parameters in an injection molding operation, oreven prevent any operator adjustment of certain parameters, based onoperator adjustment of other parameters. For instance, if an operatorsets up an injection molding machine to implement molding operatingprogram that contemplates injecting a viscous molten thermoplasticmaterial at particularly aggressive velocity in a given portion of eachinjection molding cycle, the machine may be pre-programmed to onlypermit the injection molding machine's electric, hydraulic,servo-hydraulic, or servo-driven screw to accelerate at a conservativerate of acceleration, and/or to operate at a conservative pressure,based on the manufacturer's built-in safety margin below the machine'sactual load capacity.

SUMMARY OF THE INVENTION

Embodiments within the scope of the present invention are directed tothe use of multiple controllers (i.e., a native controller and aretrofit controller) to effectively control operation of an injectionmolding machine. The controllers may determine and/or receiveinformation regarding the machine's maximum load capacity, and may alsodetermine an instantaneous (or at least periodic) present load value onthe machine. The retrofit controller of the present disclosure may causethe machine to operate at or near the maximum load value by adjustingany number of machine parameters, and dynamically adjust the rangewithin which operator-adjustable parameters in an injection moldingoperation may be manipulated to facilitate, or at least permit,operation of the injection molding machine in a manner that exploits themachine's actual load capacity during the course of its operation,thereby increasing efficiency and output. In response to operatoradjustment of various injection molding operating parameters, ratherthan constrain other operating parameters to tight ranges or preventingadjustment beyond conservative manufacturer-set safety margins, thecontroller of the present invention permits conventionally-fixedparameters to float in a manner that allows the injection moldingmachine to operate at, or near, its maximum load capacity at the newoperating conditions (which may include both machine conditions andenvironmental conditions).

In many embodiments of the present disclosure, the retrofit controlleris adapted to selectively operate the injection molding machine in amanner that allows the current load value to remain within apredetermined range below the maximum load value. By adjusting anynumber of operating parameters, the machine is capable of reacting tochanging conditions, some of which may occur during the middle of acycle, in a near-instantaneous manner, thus effectively maximizingmachine efficiency and producing the maximum number of parts possibleover a given period of time. Additionally, because the retrofitcontroller is adapted to monitor the machine in real-time, an operatorneed not actively monitor and/or adjust the machine's parameters on thefly.

In these embodiments, one and/or both of the native and retrofitcontrollers may first enter into a learning mode, during which aninitial or reference load value or curve is calculated. The initial loadvalue is calculated based on a first set of parameters and/or operatingvariables, and represents an estimated maximum load value the injectionmolding machine can maintain while avoiding failure. One of the twocontrollers then calculates a modified load value by operating theinjection molding machine based on a second set of operating variables.This second set of parameters may be values that are anywhere betweenapproximately 0.1 to 50%, preferably 0.1 to 25%, more preferably 0.1 to15%, even more preferably 0.1 to 10%, and most preferably 0.1 to 5%,including any integer or non-integer percentage within these ranges,away from the parameters used to calculate the initial load value. Theload values may be calculated using a root-mean-square approach or anyother suitable method.

Using the initial and modified load values as well as the first andsecond set of operating parameters, a reference (or maximum) load curvefor that particular injection molding system may be generated. Forinstance, a computer program associated with the controller may beprovided that interpolates load values between the measured initial andmodified load values for any operating conditions intermediate the firstand second operating conditions, and extrapolates load values foroperating conditions outside of the first and second operatingconditions. Alternately, a reference or maximum load curve may beprovided by the machine manufacturer or by the provider of the retrofitequipment, may be a theoretical value based on a predetermined maximumoperating condition, and/or may be obtainable by other means.

The operating parameters may be any combination of adjustments to theinjection molding machine, and may include environmental conditions,some of which may be within the control of the molder, such as ambienttemperature in a temperature-adjustable manufacturing facility, but somemay be outside of human control, such as barometric pressure. In someapproaches, variations in operating parameters may include adjustmentsto a barrel temperature, a clamp closing speed, a clamp opening speed, acooling time, an inject forward time, an overall cycle time, a pressuresetpoint, a screw recovery speed, and a screw velocity. Other examplesare possible and may be dependent on the particular injection moldingmachine in use.

Upon the machine entering an operational mode, the retrofit controllerselectively operates the machine based on any number of operatingparameters described herein. By adjusting the various operatingparameters, an operational load value of the machine may be maintainedbelow the reference load curve. During operation of the machine, one orboth of the controllers are adapted to actively (e.g., periodically)monitor the load values to ensure the operational load on the machineremains below values of the reference curve. The retrofit controller isfurther adapted to adjust the operating variables as needed to ensurethe operating load value remains below the reference load values.

In many of these examples, the retrofit controller may selectivelycontrol how closely the operational load is kept to the reference loadcurve by adjusting the operating parameters described herein. Forexample, depending on the particular application, the operational loadmay be held to within approximately 0.1-50% of the maximum load value,or any integer or non-integer value for percentage in that range, or anyrange formed by any of those integer values, such as 0.1-30% or from0.1-25%, 0.1-10%, or 0.1-5%.

The retrofit controller can be any type of controller, such as anelectro-mechanical controller, a circuit board, a programmable logiccontroller, an industrial computer, or any other type of controller asdescribed herein or as known in the art. The retrofit controller may beset, configured, and/or programmed with logic, commands, and/orexecutable program instructions according to the embodiments providedherein or as known in the art.

The retrofit controller is adapted to establish signal communicationbetween the retrofit controller and the injection molding machine suchthat the retrofit controller at least partially controls operation ofthe machine. Thus, the retrofit controller may connect one or moreoutputs from any number of sensors (e.g., pressure sensors, temperaturesensors, position sensors, and the like) disposed on or near the machineto one or more inputs of the retrofit controller. Connecting theretrofit controller may also include disconnecting one or more of theexisting sensor outputs from the native controller and connecting thoseexisting sensor outputs to the retrofit controller, or adding moreoutputs to one or more of the existing sensors and connecting thoseadded outputs to the retrofit controller, or combinations of these.Connecting the retrofit controller can involve one or more existingsensors already in place on the molding machine, or moving one or moreexisting sensors to new locations on the molding machine, or installingone or more new sensors on the molding machine, or combinations ofthese. The signal communication can be any kind of signal (e.g.hydraulic, pneumatic, mechanical, analog electrical, digital electrical,optical, etc.) described herein or known in the art. In someembodiments, the retrofit controller can replace the native controllerand replace all of its functions. In other embodiments of retrofitting,the retrofit controller can be added as an addition to the nativecontroller and replace less than all of its functions. In alternativeembodiments, a native controller can be reconfigured to become aretrofit controller, as described herein.

Any or all of the embodiments described in this Summary section can beperformed in any way disclosed herein or known in the art, and can beused and/or combined in any workable combination, including anyalternative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter that is regarded as thepresent invention, it is believed that the invention will be more fullyunderstood from the following description taken in conjunction with theaccompanying drawings. Some of the figures may have been simplified bythe omission of selected elements for the purpose of more clearlyshowing other elements. Such omissions of elements in some figures arenot necessarily indicative of the presence or absence of particularelements in any of the exemplary embodiments, except as may beexplicitly delineated in the corresponding written description. None ofthe drawings are necessarily to scale.

FIG. 1 illustrates an exemplary machine loading profile in which aninjection molding machine's screw velocity is plotted as a function ofpressure in accordance with various embodiments of the presentdisclosure;

FIG. 2 illustrates an elevation view of an exemplary injection moldingmachine having a retrofit controller coupled thereto in accordance withvarious embodiments of the present disclosure;

FIG. 3 illustrates portions of a control mechanism having a native and aretrofit controller in accordance with various embodiments of thepresent disclosure;

FIG. 4 illustrates a retrofit injection mold cycle as programmed to thecontrol mechanism to control the injection molding process in accordancewith various embodiments of the present disclosure;

FIG. 5 illustrates an exemplary screenshot of a controller providingperiodically updated operating values of a number of parameters inaccordance with various embodiments of the present disclosure; and

FIGS. 6A and 6B illustrate exemplary schematics of control processes ofelectric and hydraulic injection molding machine in accordance withvarious embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the drawings, an injection molding process is hereindescribed. Injection molding machines have a generally nonlinearreference or maximum loading curve 10 as illustrated in FIG. 1. Thiscurve 10 may be viewed as a graphical representation of an effect thatany number of parameters (such as, for example, velocity as a functionof operating pressure) may have on the machine. Generally speaking,operators run these machines at operating load values (which mayfluctuate over time) that are at a point well below the reference loadcurve to avoid tripping the injection molding machine manufacturer'spre-programmed alarms and/or failure modes. As FIG. 1 illustrates,injection molding machines (also referred to herein simply as“machines”) typically have absolute maximum operating values which maynot be exceeded so as to limit potential machine failure.

Machine manufacturers utilize safety buffers which act to restrictparameters from exceeding particular values that are lower than thatwhich would cause the machine to operate to its absolute maximumoperating load capacity. As illustrated by FIG. 1, points P-1 and V-1represent specified manufacturing maximum values that may not beexceeded. These values are programmed into a native controller that atleast partially controls operation of the machine. As a result of theserestrictive values, the normal available operating range 12 (as depictedby the slashed shaded area in FIG. 1) is available for use by theoperator, meaning the operating parameters may fall somewhere in thisarea.

However, the machine may still be operated using parameters that aregreater than the manufacturer's designated maximums without causingdamage to the injection molding machine. In the examples providedherein, operating parameters such as the maximum pressure areselectively increased (while remaining below the machine's specifiedabsolute maximum operating velocity value) in order to increase theavailable operating range 14 (depicted by area having circles in FIG.1). Similarly, the maximum velocity may be selectively increased (whileremaining below the machine's specified absolute maximum operatingvelocity value) in order to increase the available operating range 16(as depicted by the area having crosses in FIG. 1). Any number ofparameters may be adjusted in this way to increase the allowableoperating range of the machine. Ultimately, the entire area under themaximum load curve (up to the machine's specified absolute maximumoperating parameter values) may be used.

To enable operating parameter values beyond the manufacturer'spreprogrammed maximums, a retrofit controller is used to intercept andalter and/or generate new control signals that are sent to the injectionmolding machine. The retrofit controller may include software thatcommunicates with the native controller to “trick” the native controllerinto believing operating parameters are still within the manufacturer'smaximum allowed values while in reality, different control signals arebeing sent to the machine. In some examples, the retrofit controller maysuspend or intercept control signals originating from the nativecontroller and generate new signals to send to the machine. Otherexamples are possible, and further discussion of the retrofit controlleris provided herein.

While any number of approaches may be used to form parts, the injectionmolding machine described herein is merely exemplary and is not intendedto limit the applicability of inventive concepts in any way. Theapproaches described herein may be suitable for electric presses,servo-hydraulic presses, and other known machines. As illustrated inFIG. 2, the retrofitted injection molding machine 100 includes aninjection unit 102 and a clamping system 104. The injection unit 102includes a hopper 106 adapted to accept material in the form of pellets108 or any other suitable form. In many of these examples, the pellets108 may be a polymer or polymer-based material. Other examples arepossible.

The hopper 106 feeds the pellets 108 into a heated barrel 110 of theinjection unit 102. Upon being fed into the heated barrel 110, thepellets 108 may be driven to the end of the heated barrel 110 by areciprocating screw 112. The heating of the heated barrel 110 and thecompression of the pellets 108 by the reciprocating screw 112 causes thepellets 108 to melt, thereby forming a molten plastic material 114. Themolten plastic material 114 is typically processed at a temperatureselected within a range of about 130° C. to about 410° C.

The reciprocating screw 112 advances forward and forces the moltenplastic material 114 toward a nozzle 116 to form a shot of plasticmaterial which will ultimately be injected into a mold cavity 122 of amold 118 via one or more gates 120 which direct the flow of the moltenplastic material 114 to the mold cavity 122. In other embodiments, thenozzle 116 may be separated from one or more gates 120 by a feed system(not illustrated). The mold cavity 122 is formed between the first andsecond mold sides 125, 127 of the mold 118 and the first and second moldsides 125, 127 are held together under pressure via a press or clampingunit 124.

The press or clamping unit 124 applies a predetermined clamping forceduring the molding process which is greater than the force exerted bythe injection pressure acting to separate the two mold halves 125, 127,thereby holding together the first and second mold sides 125, 127 whilethe molten plastic material 114 is injected into the mold cavity 122. Tosupport these clamping forces, the clamping system 104 may include amold frame and a mold base, in addition to any other number ofcomponents.

Once the shot of molten plastic material 114 is injected into the moldcavity 122, the reciprocating screw 112 halts forward movement. Themolten plastic material 114 takes the form of the mold cavity 122 andcools inside the mold 118 until the plastic material 114 solidifies.Upon solidifying, the press 124 releases the first and second mold sides115, 117, which are then separated from one another. The finished partmay then be ejected from the mold 118. The mold 118 may include anynumber of mold cavities 122 to increase overall production rates. Theshapes and/or designs of the cavities may be identical, similar, an/ordifferent from each other.

The retrofitted injection molding machine 100 also includes a nativecontroller 140 which is communicatively coupled with the machine 100 viaconnection 145. The connection 145 may be any type of wired and/orwireless communications protocol adapted to transmit and/or receiveelectronic signals. In these examples, the native controller 140 is insignal communication with at least one sensor, such as, for example,sensor 128 located in the nozzle 116 and/or a sensor 129 locatedproximate an end of the mold cavity 122. It is understood that anynumber of additional sensors may be placed at desired locations of themachine 100.

The native controller 140 can be disposed in a number of positions withrespect to the injection molding machine 100. As examples, the nativecontroller 140 can be integral with the machine 100, contained in anenclosure that is mounted on the machine, contained in a separateenclosure that is positioned adjacent or proximate to the machine, orcan be positioned remote from the machine. In some embodiments, thenative controller can partially or fully control functions of themachine via wired and/or wired signal communications as known and/orcommonly used in the art.

The sensor 128 may be any type of sensor adapted to measure (eitherdirectly or indirectly) one or more characteristics of the moltenplastic material 114 located in the nozzle 116. The sensor 128 maymeasure any characteristics of the molten plastic material 114 that isknown in the art, such as, for example, pressure, temperature,viscosity, flow rate, and the like, or any one or more of any number ofadditional characteristics which are indicative of these. The sensor 128may or may not be in direct contact with the molten plastic material114. In some examples, the sensor 128 may be adapted to measure anynumber of characteristics of the injection molding machine 100 near thenozzle 116 and not just those characteristics pertaining to the moltenplastic material 114.

The sensor 128 generates a signal which is transmitted to an input ofthe native controller 140. If the sensor 128 is not located within thenozzle 116, the native controller 140 can be set, configured, and/orprogrammed with logic, commands, and/or executable program instructionsto provide appropriate correction factors to estimate or calculatevalues for the measured characteristic in the nozzle 116.

The sensor 129 may be any type of sensor adapted to measure (eitherdirectly or indirectly) one or more characteristics of the moltenplastic material 114 to detect its presence and/or condition in the moldcavity 122. In various embodiments, the sensor 129 may be located at ornear an end-of-fill position in the mold cavity 122. The sensor 129 maymeasure any number of characteristics of the molten plastic material 114and/or the mold cavity 122 that is known in the art, such as pressure,temperature, viscosity, flow rate, etc. or one or more of any othercharacteristics that are indicative of any of these. The sensor 129 mayor may not be in direct contact with the molten plastic material 114.

The sensor 129 generates a signal which is transmitted to an input ofthe native controller 140. If the sensor 129 is not located at theend-of fill position in the mold cavity 122, the native controller 140can be set, configured, and/or programmed with logic, commands, and/orexecutable program instructions to provide appropriate correctionfactors to estimate or calculate values for the measured characteristicat the end-of-fill position. It is understood that any number ofadditional sensors may be used to sense and/or measure operatingparameters.

The native controller 140 is also in signal communication with the screwcontrol 126. In these embodiments, the native controller 140 generates asignal which is transmitted from an output of the native controller 140to the screw control 126. The native controller 140 can control anynumber of characteristics of the machine, such as, for example,injection pressures (by controlling the screw control 126 to advance thescrew 112 at a rate which maintains a desired melt pressure of themolten plastic material 114 in the nozzle 116), barrel temperatures,clamp closing and/or opening speeds, cooling time, inject forward time,overall cycle time, pressure setpoints, screw recovery speed, and screwvelocity. Other examples are possible.

The signal or signals from the native controller 140 may generally beused to control operation of the molding process such that variations inmaterial viscosity, mold temperatures, melt temperatures, and othervariations influencing filling rate are taken into account by the nativecontroller 140. Adjustments may be made by the native controller 140 inreal time or in near-real time (that is, with a minimal delay betweensensors 128, 129 sensing values and changes being made to the process),or corrections can be made in subsequent cycles. Furthermore, severalsignals derived from any number of individual cycles may be used as abasis for making adjustments to the molding process. The nativecontroller 140 may be connected to the sensors 128, 129, the screwcontrol 126, and or any other components in the machine 100 via any typeof signal communication known in the art.

As illustrated schematically in FIGS. 2 and 3, the retrofit controller150 is generally similar to the native controller 140. The retrofitcontroller 150 is electrically coupled to the native controller 140 viaany number of methods such that the retrofit controller 150 and thenative controller 140 are in signal communication. The retrofitcontroller 150 is adapted to control operation of the injection moldingmachine 100 directly and/or by controlling the output of the nativecontroller 140.

The native controller 140 includes software 141 adapted to control itsoperation, any number of hardware elements 142 (such as, for example, amemory module and/or processors), any number of inputs 143, any numberof outputs 144, and any number of connections 145. The software 141 maybe loaded directly onto a memory module of the native controller 140 inthe form of a non-transitory computer readable medium, or mayalternatively be located remotely from the native controller 140 and bein communication with the native controller 140 via any number ofcontrolling approaches. The software 141 includes logic, commands,and/or executable program instructions which may contain logic and/orcommands for controlling the injection molding machine 100 according toan original mold cycle. The software 141 provided by manufacturersincludes preprogrammed maximum safe operating values of any number ofparameters which are designed to limit the risk of machine damage and/orfailure. The software 141 may or may not include an operating system, anoperating environment, an application environment, and/or a userinterface.

The hardware 142 uses the inputs 143 to receive signals, data, andinformation from the injection molding machine being controlled by thenative controller 140. The hardware 142 uses the outputs 144 to sendsignals, data, and/or other information to the injection moldingmachine. The connection 145 represents a pathway through which signals,data, and information can be transmitted between the native controller140 and its injection molding machine 100. In various embodiments thispathway may be a physical connection or a non-physical communicationlink that works analogous to a physical connection, direct or indirect,configured in any way described herein or known in the art. In variousembodiments, the native controller 140 can be configured in anyadditional or alternate way known in the art.

The retrofit controller 150 includes components that are similar tothose of the native controller 140, such as a software 151 adapted tocontrol its operation, any number of hardware elements 152 (such as, forexample, a memory module and/or processors), any number of inputs 153,any number of outputs 154, and any number of connections 155. Thesoftware 151 may be loaded directly onto a memory module of the nativecontroller 150, or may alternatively be located remotely from the nativecontroller 150 and be in communication with the native controller 150via any number of controlling approaches. The software 151 includeslogic, commands, and/or executable program instructions which maycontain logic and/or commands for controlling the injection moldingmachine 100 according to a retrofit mold cycle. Unlike the original moldcycle, in the retrofit mold cycle, the maximum allowable operatingparameters are no longer fixed to permanent values and may be variableso long as the total overall loading of the injection molding machine100 remains below a maximum value.

The connection 145 is illustrated as being in common with a connection155, wherein the common connection represents a pathway through whichsignals, data, and information can be transmitted: a) between theretrofit controller 150, the native controller 140 and the injectionmolding machine 100, b) between the retrofit controller 150 and theinjection molding machine 100, and c) between the retrofit controller150 and the native controller 140. In various embodiments these pathwaysmay be physical connections or non-physical communication links thatwork analogous to physical connections, direct or indirect, configuredin any way described herein or known in the art. In various embodiments,the native controller 140 and the retrofit controller 150 can beconfigured in any additional or alternate way known in the art.

FIG. 3 illustrates connecting a particular output 144 from the nativecontroller 140, which is used as a particular input 153 to the retrofitcontroller 150. In various embodiments disclosed herein, theretrofitting of the injection molding machine 100 includes establishingsignal communication between: a) an inject forward output 156 fromoutputs 144 of the native controller 140, and b) one of the inputs 153of the retrofit controller 150. The native controller 140 can be set,configured, and/or programmed with logic, commands, and/or executableprogram instructions such that the inject forward output 156 signalswhen the plastic injecting should (and/or should not) occur during amold cycle of the molding machine 100.

As an example, the native controller 140 can turn “on” the injectforward output 156 when the plastic injecting should occur, and can turn“off” the inject forward output 156 when the plastic injecting shouldnot occur. The retrofit controller 150 can use the state of the injectforward output 156 as a condition for injecting plastic in the retrofitmold cycle. This signal communication allows the native controller 140to hand-off control of the plastic injection to the retrofit controller150 for the plastic injecting portion and/or any other portion of theretrofit mold cycle. In various embodiments, the function of the injectforward output 156 can be accomplished by the native controller 140sending to the retrofit controller 150 one or more additional oralternate signals, data, and/or information, which are equivalent to aninject forward output 156, using any known approaches in the art.

FIG. 3 further illustrates moving a particular output from the nativecontroller 140 to the retrofit controller 150. In various embodimentsdisclosed herein, the retrofitting includes: a) disconnecting signalcommunication between an injection control output 147 of the nativecontroller 140 and a control input of an injection unit of the moldingmachine 100 (signal illustrated by a phantom line), and b) establishingsignal communication between an injection control output 157 of theretrofit controller 150 and the control input of the injection unit ofthe molding machine 100 (signal illustrated by a solid line). Theretrofit controller 150 can be set, configured, and/or programmed withlogic, commands, and/or executable program instructions such that theinjection control output 157 signals the injection unit regarding therate at which injecting should occur during plastic injecting of aretrofit mold cycle of the molding machine.

As an example, the retrofit controller 150 can generate the injectioncontrol output 157 as an analog control voltage, which scales from aparticular low value (representing a minimum injection rate) to aparticular high value (representing a maximum injection rate). Theinjection unit can use the state of the inject control output 157 as theinput for controlling the rate of injecting plastic in the retrofit moldcycle. The rate of injecting, in turn, directly affects operating valuessuch as the injection pressure of the molten plastic in the machine 100.As a result, the injection control output 157 can effectively be used tocontrol injection pressures in the retrofitted injection molding machine100, according to any of the embodiments disclosed herein. This signalcommunication also allows the retrofit controller 150 to replace controlof the plastic injection by the native controller 140 in the retrofitmold cycle. In various embodiments, the function of the injectioncontrol output 157 can be accomplished by the retrofit controller 150generating one or more additional or alternate signals, data, and/orinformation, which are equivalent to an injection control output, andsending such to one or more additional or alternate machine components,which partially or fully control operating parameters of the machine 100in any way known in the art. For example, in one alternative embodiment,the retrofit controller 150 may at least partially control injectionpressures of the machine 100 by controlling a rate of melt flow throughthe nozzle 116. In various embodiments, the retrofitting can alsoinclude rerouting the disconnected injection control output 147 to oneof the inputs 153 of the retrofit controller 150. Other examples arepossible.

The injection molding machine 100 may also include a disable switch 158,which can be provided with the retrofitting, as described herein. Thedisable switch 158 can allow a user of the retrofitted injection moldingmachine to select a mode of injection molding that disables the retrofitcontroller 150 such that the machine 100 and the native controller 140mold production versions (i.e. parts made using production conditions onthe molding machine 100, wherein the parts have acceptable part quality)of the plastic part according to the original mold cycle. In variousembodiments disclosed herein, the retrofitting process includesestablishing signal communication between: a) a user-controlled output159 from the disable switch 158, and b) one of the inputs 153 of theretrofit controller 150. The retrofit controller 150 can be set,configured, and/or programmed with logic, commands, and/or executableprogram instructions such that when the user-controlled output 159provides a particular signal, the retrofit controller 150 does notcontrol plastic injecting during a mold cycle of the molding machine100.

As an example, when the user-controlled output 159 is turned “on,” theinjecting function of the retrofit controller 150 is disabled and doesnot control the plastic injecting, and when the user-controlled output159 is turned “off,” the injecting function of the retrofit controller150 is not disabled and does control the plastic injecting. The retrofitcontroller 150 can also be set, configured, and/or programmed withlogic, commands, and/or executable program instructions such that whenthe injecting function of the retrofit controller 150 is disabled, theretrofit controller 150 can receive the control output 147 from thenative controller 140 (as described above) and pass that received signalto the control input of the injection unit of the molding machine 100.As a result, when the injecting function of the retrofit controller 150is disabled, the native controller 140 can effectively control theplastic injecting (with the passed through signal) and the retrofittedmolding machine 100 can still operate, although using an original moldcycle which is likely to be relatively less efficient then the retrofitmold cycle. In various embodiments, the function of the disable switch158 and the user-controlled output 159 can be accomplished by one ormore additional or alternate user input devices and/or signals, data,and/or information which are equivalent, in any workable way known inthe art.

FIG. 4 provides an illustration of a retrofit injection mold cycle 300as programmed on the native controller 140 and the retrofit controller150 of FIGS. 2 and 3, for controlling the retrofitted injection moldingmachine 100. The retrofit mold cycle 300 includes an operating sequenceof injecting molten plastic 310, according to control 302 by theretrofit controller 150, and subsequently performing other functionsaccording to control 301 by the native controller 140. The injecting ofthe molten plastic 310 includes an initial injecting portion 315, afilling portion 316, which includes using a target pressure 316-t, and adecreasing pressure portion 317. The native controller 140 and retrofitcontroller 150 can use various signal communications, as describedherein and known in the art, to share control of the retrofittedinjection molding machine 100 during the retrofit mold cycle. Theinjecting of the molten plastic 310 can be partially or fully performedin any way described herein for a retrofit mold cycle. The otherfunctions of the cycle include cooling the plastic 320, opening the mold330, ejecting the part from the mold 340, and closing the mold 350. Anynumber of additional functions may be performed by either the retrofitcontroller 150 and/or the native controller 140.

In order to run the retrofit injection mold cycle, machine load valuesmust be determined and/or calculated for the injection loading machine100, preferably in real time, continuously, semi-continuously,periodically, or at at least one or a plurality of locations during thecourse of an injection molding cycle.

In some embodiments, maximum and/or reference load values for themachine 100 are provided by the manufacturer and/or are readilyobtainable.

In other examples, the maximum load may be calculated by causing theinjection molding machine 100 to enter a learning mode during which aninitial load value is calculated based on operating the machine 100according to a first defined set of parameters. Accordingly, this firstset of parameters would be interpreted as a “maximum loading” value. Amodified load value is then calculated by operating the machine 100according to a second defined set of parameters. In some examples, theloading may be increased by a specified percentage to reach an absolutemaximum loading of the machine. By modifying the parameters to thesecond defined set, a relative weighting of what each factor contributesto the overall loading of the machine can be determined. As an example,by increasing the cooling time by a specified percentage, the amount themachine loading changes can be calculated. The second set of parameterscan be experimentally determined to understand the maximum amount ofchange that is allowable before a noticeable degradation in part qualityis observed. As a result, in some embodiments, a suitable operatingrange for each parameter is determined and thereafter used to formsatisfactory parts.

This second defined set of parameters can differ from the first definedset of parameters, preferably by at least approximately 5-35% in orderto allow the reference load curve to be optimally interpolated andextrapolated. The retrofit controller 150 and/or the native controller140 then generates and stores a reference load curve that is based onthe first and second operating parameters via extrapolation and/or anyother suitable method. For example, the parameters may be determined viaan iterative, “closed-loop” process known in the art. In these examples,limits and operating instructions must be established and provided sothe controller can “learn” how far the parameters may be changed tomaintain safe operation of the injection molding machine. In furtherembodiments, dependent variables may be added where modifying any numberof variables may result in other variables automatically changing tostay within the established limits.

In some examples, it may be necessary to identify operating speed,torque settings, estimated load values, the particular machine geometry(e.g., screw pitch or other details), and the type of plastic beingused. Other variables may also need to be identified. It is understoodthat the reference load curve may be calculated via any other suitablemethod known in the art such as by experientially monitoring systemperformance at a peak period of time and storing and using these valuesas maximums. In other approaches, the maximum load value may be atheoretical value based on the motor and/or drive specifications for agiven injection molding machine.

Upon determining and/or establishing a reference or maximum load curve,the learning mode is complete, and the injection molding machine 100 isplaced in an operational mode wherein it is operated in a manner thatdoes not exceed the maximum load value at any point but may approach themaximum load value to obtain peak efficiency. Alternately, the learningmode may remain open and the reference or maximum load curve couldcontinually or periodically be regenerated based on new reference loaddata. If the operational load value were to exceed the maximum loadvalue, the machine 100 may overheat, risk damage to one or more of itscomponents, and/or fail. The machine 100 may be adapted to accept a userinput designating how close an operational load must be to the maximumload allowable by the machine. In some embodiments, a user may wish tooperate the machine 100 within approximately 50% and approximately 100%of the maximum load at all times, without exceeding the maximum load atany time. In preferred embodiments, the machine may be configured tooperate at any numerical value between approximately 60-99% of themachine's maximum load. If the operational load falls outside of thisrange, the retrofit controller 150 is adapted to selectively controloperation of the machine to cause the operational load to be within thisrange, with a pre-programmed hierarchy of operational parameteradjustments to be made to bring the IM machine back within the desiredrange. In some examples, sensors 128, 129 and/or any other devices maydetermine values associated with the machine's 100 operation andtransmit these data to the native controller 140 and/or the retrofitcontroller 150. The current operating values are then compared to thereference load curve to determine whether the machine is operatingwithin the desired range.

In some embodiments, any or all of the initial load value, the modifiedload value, and/or the current operational load value are calculatedusing a root-mean-square (or RMS) calculation in which the operatingcurrent and/or voltage values are periodically measured to determine amean value. Power consumption can be measured using any number ofapproaches known in the art such as, for example, by usingcurrent/voltage probes. To measure power consumption, RMS voltage andRMS current are calculated and multiplied together. The powerconsumption may also be calculated using the following formula:POWER=SQRT(I₀^2+I₁^2+I₂^2+ . . . I_(n)^2)*SQRT(V₀^2+V₁^2+V₂^2+ . . .+V_(n)^2) where I_(n) and V_(n) represent scans of the processor. Ifthese values are calculated at a high enough rate, a machine's powerloading may be provided. This calculation is then reset or repeated witheach given shot or segment of control of interest (for example, theinjection phase, the hold phase, the recovery phase, etc.). In otherexamples, a machine capacity load calculation or any other calculationknown in the art may be used to determine the machine's load.

An exemplary operating screen or display 500 of the native controller140 and/or the retrofit controller 150 is illustrated in FIG. 5. Thenative controller 140 and/or the retrofit controller 150 may sense,determine, calculate, and/or display information relating to operationof the machine 100 in a graphical manner to allow an operator toidentify how the machine 100 is currently operating. The nativecontroller 140 and/or the retrofit controller 150 may also storehistorical data for the operator to review at a later date and toperform any number of analytical calculations. The display 500 mayprovide energy consumption metrics for different phases of the injectionmolding cycle, and may sum this information to provide a total loadvalue.

In some embodiments, the retrofit controller 150 may incorporate anynumber of approaches to providing periodic, accurate tracking and/oradjusting of machine parameters in real or near-real time. For example,the retrofit controller 150 may incorporate feedback control componentsand/or systems which compare real-time sensed operating values withanticipated operating values and applying corrective action tocompensate for the difference between the sensed values.

In some examples, the retrofit controller 150 may be a closed loopcontroller which provides feedback and trim control during the moldcycle. The feedback trim control provides modification to bothsteady-state response and control system dynamics. By altering thefeedback signal of the control system (e.g., adding and/or subtracting aPID controlled trim signal), either the native controller 140 and/or theretrofit controller 150 may perform the desirable process. It isunderstood that any number of feedback controllers and/or systems knownthose having skill in the art may be used.

As a non-limiting example and as illustrated schematically by FIGS. 6Aand 6B, the retrofit controller 150 may be adapted to include feedbackcontrol (e.g., a trim control process as illustrated by FIG. 6A) whichcan include a number of components coupled to the injection moldingmachine 600 via any number of electrical coupling approaches. Thefeedback control may be applied to any machine configuration, includingelectric, hydraulic, servo-hydraulic, servo-driven, and any otherconfigurations. In addition to the components of the injection moldingmachine 600 previously described herein with regard to the precedingfigures, the process may utilize any number of sensors 602 (e.g., acavity sensor and a nozzle sensor), a load calculation module 604, afirst pressure setpoint 606, a first summer 608, a first PID controller610, a second summer 612, a second pressure setpoint 614 (which may beequal in value to that of the first pressure setpoint 606), a thirdsummer 616, a second PID controller 618, and a valve or drive 620. It isunderstood that any number of additional components used in feedbackcontrol processes may also be used to provide control. Further, it isunderstood that the native controller may supply the retrofit controllerwith any number of sensed values not illustrated in FIGS. 6A and/or 6B.

As illustrated in FIG. 6A, the sensor and/or sensors 602 transmit asignal to the load calculation module 604 to determine the currentoperational load value. This value is transmitted to the first summer608 which compares the value to the first pressure setpoint 606 andgenerates an error signal to be transmitted to the first PID controller610. The first PID controller 610 then generates a load signal andtransmits the signal to the second summer 612, which compares the signalto the current operational load value. The second summer 612 generates avoltage signal indicative of an operating pressure based on the receivedsignals, and is compared to the second pressure setpoint 614 value atthe third summer 616. Depending on the machine, the system environment,and additional factors, the process may transmit signals at differentvoltage scales. For example, the signals may range between 4-20 mV,−10-10V, 0-10V, and any other suitable range. In some embodiments, thesignal ranges may also vary based on the type of signal being measured(e.g., a temperature, pressure, and/or position measurement). An errorsignal is again sent to the second PID controller, which generates avoltage signal representative of a valve position for the valve or drive620. Upon receiving this signal, the valve 620 adjusts and transmits apressure to the injection molding machine 600 for operation.

The process illustrated schematically in FIG. 6B depicts the use of acontrol loop in an exemplary standard (e.g., hydraulic) press anddiffers from the process in FIG. 6A in that a single control loop isused to determine and cause modifications to the system. In thesemachines, the feedback loop may be different from the control used in anelectric process. Some considerations when controlling a hydraulic pressinclude additional contributing factors on the load such as hydraulicpressure (including the pressure in hoses, valves, and othercomponents), oil temperatures (where, in some examples, the hybrid pressmay shut down due to overloading), and a PID tuning rate. Other examplesare possible.

In FIG. 6B, the sensor and/or sensors 602 transmit a signal to the loadcalculation module 604 to determine the current operational load value.This value is transmitted to the summer 608 which compares the value tothe pressure setpoint 606 and generates an error signal to betransmitted to the PID controller 610. The PID controller then generatesa voltage signal representative of a valve position for the valve ordrive 620. Upon receiving this signal, the valve 620 adjusts andtransmits a pressure to the injection molding machine 600 for operation.In some examples, the controller may adjust the dwell, cooling, and/oreject timing prior to adjusting valve pressure.

In some approaches, parameters of the injection molding machine 100 maybe adjusted in any number of ways to effectuate a change to the currentoperational load. For example, changes may be made to a barreltemperature, a clamp closing speed, a clamp opening speed, a coolingtime, an inject forward time, an overall cycle time, a pressuresetpoint, a screw recovery speed, and/or a screw velocity to adjust thecurrent operational load. It is understood that changing any and/or allof these parameters may have an effect on the operational load, thusthere may be countless approaches to modifying these parameters toaccomplish an increase or decrease in the operational load value.

For example, in some embodiments, by decreasing the barrel temperature,the machine's loading increases, as, for example, the lower barreltemperature may result in relatively higher viscosity of the moltenpolymeric material to be injected into the mold cavity. By decreasingthe clamp closing and opening speed, the operational load value willdecrease. By decreasing the cooling (or dwell) time, the operationalload value will increase. By decreasing the inject forward time (e.g.,fill and pack times), the pressure setpoint, screw recovery speed, andscrew velocity, the machine's loading values will decrease. Bydecreasing the overall cycle time, the machine's loading will increase.It is understood that for any of the above examples, increasing theparameter may result in an opposite effect on the machine's loading.Other examples of parameters which may be adjusted are possible. Thesoftware 151 of the retrofit controller 150 is adapted to selectivelyadjust any number of these parameters to increase or decrease the loadvalue as desired to keep the current operational load within the desiredrange.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application and any patent application or patent to which thisapplication claims priority or benefit thereof, is hereby incorporatedherein by reference in its entirety unless expressly excluded orotherwise limited. The citation of any document is not an admission thatit is prior art with respect to any invention disclosed or claimedherein or that it alone, or in any combination with any other referenceor references, teaches, suggests or discloses any such invention.Further, to the extent that any meaning or definition of a term in thisdocument conflicts with any meaning or definition of the same term in adocument incorporated by reference, the meaning or definition assignedto that term in this document shall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A method of retrofitting an injection moldingmachine, the method comprising: retrofitting an injection moldingmachine with a retrofit controller, the injection molding machineincluding a native controller adapted to control operation of theinjection molding machine; entering a learning mode of at least one ofthe native controller or the retrofit controller to calculate an initialload value of the injection molding machine based on a first set ofoperating parameters; calculating a modified load value of the injectionmolding machine by operating the injection molding machine based on asecond set of operating parameters; generating a reference load curvebased on at least the first set of operating parameters and the secondset of operating parameters; entering an operational mode of theretrofit controller; and using the retrofit controller, selectivelyoperating the injection molding machine such that an operational loadvalue of the injection molding machine remains at or below the referenceload curve.
 2. The method of claim 1, wherein the retrofit controllercomprises a closed loop controller adapted to permit the injectionmolding machine unit to operate within 50% of the reference load value.3. The method of claim 1, further comprising establishing signalcommunication between an output of the retrofit controller and theinjection molding machine such that the retrofit controller at leastpartially controls operation of the injection molding machine.
 4. Themethod of claim 1, wherein the first set of operating parameters and thesecond set of operating parameters comprise adjustments to at least oneof barrel temperature, clamp closing speed, clamp opening speed, coolingtime, inject forward time, overall cycle time, pressure setpoint, screwrecovery speed, and screw velocity.
 5. The method of claim 1, whereinthe initial load value is calculated by sensing at least one of a nozzlepressure, injection pressure, screw velocity, and voltage over apredetermined per-cycle period of time and calculating a load valueusing the sensed data.
 6. The method of claim 1, wherein the modifiedload value is calculated by sensing at least one of a nozzle pressure,injection pressure, screw velocity, and voltage over a predeterminedper-cycle period of time and calculating a load value using the senseddata.
 7. The method of claim 1, wherein the second set of operatingparameters comprise a difference of approximately 0.1-50% from the firstset of operating parameters.
 8. The method claim 1, wherein selectivelyoperating the injection molding machine comprises selectively adjustingat least one of barrel temperature, clamp closing speed, clamp openingspeed, cooling time, inject forward time, overall cycle time, pressuresetpoint, screw recovery speed, and screw velocity.
 9. The method ofclaim 1, wherein the reference load curve provides an estimated maximumload value the injection molding machine can maintain while avoidingfailure.
 10. The method of claim 1, further comprising periodicallymonitoring an operating load of the injection molding machine to ensurethe operating load is within a determined range of the reference loadcurve.
 11. The method of claim 1, wherein at least one of the initialload value, the modified load value, and the operational load value iscalculated by at least one of a root-mean-square load calculation and amaximum machine capacity load calculation.
 12. The method of claim 11,wherein a total machine load value is used to calculate the maximummachine capacity load calculation.